In the case a gating-member (valve disc) that shuts an exhaust port by close contact with a gate seal face provided on the exhaust port is provided, a means for closing a gating-member retreat aperture is equipped so that no invasion or no adhesion of foreign matters will occur in the gating-member retreat room when a gating-member is retreated from the exhaust port.
Japanese Patent Application Laid Open No. 7-42872 has described a technique for closing a gating-member retreat aperture, wherein a cylindrical shutter is provided in the exhaust passage that forms an exhaust port and the cylindrical shutter is moved in the exhaust passage to shut a gating-member retreat aperture on retreat of the gating-member.
Japanese Patent Application Laid Open No. 3-239884 has described an ultra-high vacuum gate valve. The ultra-high vacuum gate valve is comprised of a valve box, a valve seat, a valve plate having an opening, a valve bar connected to the valve plate, a valve bar driving mechanism, a valve plate presser, and a stretchable bellows interposed and connected between the valve box, the valve seat, and the valve presser, wherein the valve plate is always in contact with the valve seat and the valve plate presser so that the dead space in the valve box is clogged or shut when the valve plate is in the open and the close positions.